Combination products for treating cancer

ABSTRACT

The present invention concerns products containing (i) at least one nucleic acid sequence coding for the human somatostatin 2 receptor protein (sst2) having the sequence SEQ ID NO: 1, ortholog or derivative thereof, (ii) at least one nucleic acid sequence coding for the human deoxycytidine kinase protein (dck) having the sequence SEQ ID NO:2, ortholog or derivative thereof, (iii) at least one nucleic acid sequence coding for the human uridine monophosphate kinase protein (umk) having the sequence SEQ ID NO: 3 ortholog or derivative thereof, and (iv) gemcitabine, as a combined preparation for simultaneous, separate, or sequential use for treating cancer in a subject.

This application claims the priority of the patent application EP 07301447.4 filed on Oct. 10, 2007, which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to the field of cancer, and in particular to a new products, compositions, plasmid vector and methods for cancer therapy.

BACKGROUND OF THE INVENTION

Among cancer, pancreatic cancer is one of the most aggressive and devastating human malignancies. Its aggressiveness is illustrated by the fact that the number of estimated pancreatic cancer cases and number of pancreatic cancer-related deaths are almost identical with a minimal 5-year survival rate of 2%. Pancreatic cancer ranks at the fifth leading cause of cancer-related deaths in Western countries. So far, neither early detection nor treatment of advanced disease is possible: 85% of lesions are unresectable at the time of diagnosis, resulting in a median survival time of 4-5 months.

These dismal statistics are mainly consistent with the propensity of these tumors to metastasize when small and undetectable, and the intrinsic resistance of pancreatic cancer cells to cytotoxic agents and radiotherapy.

As another aggressive cancer, hepatocellular carcinoma (hepatocarcinoma, HCC) is the most common primary malignancy of the liver and the fourth most common cancer worldwide with an incidence of 1,000,000 new cases per year. It represents the 3^(rd) cause of death by cancer in the world. In France, as in other industrialized countries, its incidence is rising steadily due to the hepatitis C virus pandemic. HCC develops from cirrhosis: the 5-year probability for cirrhotic patients to develop HCC is almost 20%. The three main curative therapeutic modalities currently used for HCC are hepatic resection, percutaneous destruction of the tumor (radiofrequency) and orthotopic liver transplantation. These options may be used in patients with so called <<small>> HCC (<5 cm) with good results (70% 5 year survival and <25% recurrence rate for transplantation). Unfortunately, such therapeutic options are only accessible to less than 50% of the patients diagnosed with HCC. Therefore, the bulk of patients cannot benefit from curative therapeutic options because of large tumor size or underlying liver disease. For these reasons, new diagnosis modalities and therapies are needed. Up to now, no chemotherapy is efficient and thus indicated in HCC.

Consequently, there is an urgent need for therapies to treat cancer, like pancreatic cancer or hepatocellular cancer, and metastatic cancer specifically, that are more effective than current regimens.

SUMMARY OF THE INVENTION

In a first aspect, the present invention relates to products containing:

-   -   (i) at least one nucleic acid sequence coding for the human         somatostatin 2 receptor protein (SST2) having the sequence SEQ         ID NO:1, ortholog or derivative thereof,     -   (ii) at least one nucleic acid sequence coding for the human         deoxycytidine kinase protein (DCK) having the sequence SEQ ID         NO:2, ortholog or derivative thereof,     -   (iii) at least one nucleic acid sequence coding for the human         uridine monophosphate kinase protein (UMK) having the sequence         SEQ ID NO:3, ortholog or derivative thereof, and     -   (iv) gemcitabine,     -   as a combined preparation for simultaneous, separate, or         sequential use for treating cancer in a subject.

In a second aspect, the present invention relates to a method for treating cancer comprising the step of simultaneously, separately, or sequentially administrating to a subject in need thereof a therapeutically effective amount of:

-   -   (i) at least one nucleic acid sequence coding for the human         somatostatin 2 receptor protein (SST2) having the sequence SEQ         ID NO: 1, ortholog or derivative thereof,     -   (ii) at least one nucleic acid sequence coding for the human         deoxycytidine kinase protein (DCK) having the sequence SEQ ID         NO: 2, ortholog or derivative thereof,     -   (iii) at least one nucleic acid sequence coding for the human         uridine monophosphate kinase protein (UMK) having the sequence         SEQ ID NO: 3, ortholog or derivative thereof, and     -   (iv) gemcitabine.

In a third aspect, the present invention relates to a pharmaceutical composition comprising:

-   -   (i) at least one nucleic acid sequence coding for the human         somatostatin 2 receptor protein (SST2) having the sequence SEQ         ID NO: 1, ortholog or derivative thereof,     -   (ii) at least one nucleic acid sequence coding for the human         deoxycytidine kinase protein (DCK) having the sequence SEQ ID         NO: 2, ortholog or derivative thereof,     -   (iii) at least one nucleic acid sequence coding for the human         uridine monophosphate kinase protein (UMK) having the sequence         SEQ ID NO: 3, ortholog or derivative thereof, and     -   (iv) optionally a pharmaceutically acceptable carrier.

In a forth aspect, the present invention finally relates to a plasmid vector having the sequence SEQ ID NO:11, and comprising nucleic acid sequences coding for the Homo sapiens somatostatin 2 receptor protein and for a polypeptide comprising the two proteins Homo sapiens deoxycytidine kinase protein (dck) and Homo sapiens uridine monophosphate kinase protein (umk) linked by the cleavable FMDV (Foot-and-Mouth-Disease virus) 2A peptide.

BRIEF DESCRIPTION OF THE DRAWINGS

The FIG. 1 shows the schematic map of pHNeo Sst2 DCK::UMK (7548 pb) plasmid (SEQ ID NO: 11).

The FIG. 2 shows the schematic map of pHDuo14 LGFP-dckumk2A (7368 pb) plasmid vector.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the sense of the present application, the cancer is preferably a metastatic cancer, like the pancreatic cancer and hepatocellular carcinoma, and most preferably an exocrine pancreatic cancer.

Metastase corresponds to the process by which a cancer spreads from the place at which it first arose as a primary tumor to distant locations in the body. Since this process is very particular in cancer progression, it is generally necessary to use specific regimen in order to inhibit metastazing.

The inventors have established that the combined intra-tumoral injection of an expression vector coding for SST2, DCK and UMK associated with a gemcitabine administration results in an extensive and surprising decrease of metastasis sites.

Accordingly, and in a preferred embodiment, the present invention is directed to the inhibition of tumor spread out—i.e., the inhibition of tumor metastazing-.

The term subject refers to a mammal and preferably to a human.

As used herein, Gemcitabine refers to Gemcitabine HCl/Chlorhydrate, marketed by ELI LILLY under the trademark GEMZAR®, which is a nucleoside analogue that exhibits antitumor activity and belongs to a general group of chemotherapy drugs known as antimetabolites. Gemcitabine prevents cells from producing DNA and RNA by interfering with the synthesis of nucleic acids, thus stopping the growth of cancer cells and causing them to die.

Gemcitabine which is disclosed in International PCT application WO 97/21719 is a synthetic glucoside analog of cytosine, which is chemically described as 1-(2′-Deoxy-2′,2′-difluoro-[beta]-D-ribofuranosyl)-4-aminopyrimidin-2-one hydrochloride or 2′-deoxy-2′,2′-difluorocytidine monohydrochloride [beta] isomer).

As used herein, the term “orthologs” refers to proteins in different mammal species than the proteins SEQ ID NO: 1, SEQ ID NO: 2 or SEQ ID NO: 3 in Homo sapiens that evolved from a common ancestral gene by speciation. One of skill in the art in view of the specification and of its general knowledge can simply identify such orthologs.

As an example of such orthologs, one can cite the somatostatin 2 receptor proteins in Mus musculus (SEQ TD NO: 4) and in Rattus norvegicus (SEQ ID NO: 5), the deoxycytidine kinase protein in Mus musculus (SEQ ID NO: 6), in Rattus norvegicus (SEQ ID NO: 7) and in Bos Taurus (SEQ ID NO: 8), or the uridine monophosphate kinase protein in Rattus norvegicus (SEQ ID NO: 9).

As used herein, the term “derivatives”′ refer to a polypeptide having a percentage of identity of at least 80% with complete SEQ ID NO: 1, SEQ ID NO: 2 or SEQ ID NO: 3, or orthologs thereof, preferably of at least 90%, as an example of at least 95%, and more preferably of at least 99%.

As used herein, “percentage of identity” between two amino acids sequences, means the percentage of identical amino-acids, between the two sequences to be compared, obtained with the best alignment of said sequences, this percentage being purely statistical and the differences between these two sequences being randomly spread over the amino acids sequences. As used herein, “best alignment” or “optimal alignment”, means the alignment for which the determined percentage of identity (see below) is the highest. Sequences comparison between two amino acids sequences are usually realized by comparing these sequences that have been previously align according to the best alignment; this comparison is realized on segments of comparison in order to identify and compared the local regions of similarity. The best sequences alignment to perform comparison can be realized, beside by a manual way, by using the global homology algorithm developed by SMITH and WATERMAN (Ad. App. Math., vol. 2, p: 482, 1981), by using the local homology algorithm developed by NEDDLEMAN and WUNSCH (J. Mol. Biol., vol. 48, p: 443, 1970), by using the method of similarities developed by PEARSON and LIPMAN (Proc. Natl. Acd. Sci. USA, vol. 85, p: 2444, 1988), by using computer softwares using such algorithms (GAP, BESTFIT, BLAST P, BLAST N, FASTA, TFASTA in the Wisconsin Genetics software Package, Genetics Computer Group, 575 Science Dr., Madison, Wis. USA), by using the MUSCLE multiple alignment algorithms (Edgar, Robert C., Nucleic Acids Research, vol. 32, p: 1792, 2004). To get the best local alignment, one can preferably used BLAST software, with the BLOSUM 62 matrix, or the PAM 30 matrix. The identity percentage between two sequences of amino acids is determined by comparing these two sequences optimally aligned, the amino acids sequences being able to comprise additions or deletions in respect to the reference sequence in order to get the optimal alignment between these two sequences. The percentage of identity is calculated by determining the number of identical position between these two sequences, and dividing this number by the total number of compared positions, and by multiplying the result obtained by 100 to get the percentage of identity between these two sequences.

According to another preferred embodiment, the Homo sapiens deoxycytidine kinase protein (dck) having the sequence SEQ ID NO: 2, ortholog or derivative thereof, and the Homo sapiens uridine monophosphate kinase protein (umk) having the sequence SEQ ID NO: 3, ortholog or derivative thereof, are encoded by a single nucleic acid sequence.

Preferably, said at least one nucleic acid sequence encodes for a polypeptide comprising the two proteins Homo sapiens deoxycytidine kinase protein (dck) and Homo sapiens uridine monophosphate kinase protein (umk) linked by the cleavable FMDV (Foot-and-Mouth-Disease virus) 2A peptide, which polypeptide has the sequence SEQ ID NO: 10.

According to still another preferred embodiment, the nucleic acids encoding somatostatin 2 receptor protein (sst2), deoxycytidine kinase protein (dck), and/or uridine monophosphate kinase protein (umk) are operatively linked to a gene expression sequence, which directs the expression of nucleic acids within an eukaryotic cell. The “gene expression sequence” is any regulatory nucleotide sequence, such as a promoter sequence or promoter-enhancer combination, which facilitates the efficient transcription and translation of the nucleic acid to which it is operatively linked. The gene expression sequence may, for example, be a mammalian or viral promoter, such as a constitutive or inducible promoter. In the plasmid designed for the present concept, the two genes (sst2 and dck::umk fusion) are under the control of two different promoters sensitive to hypoxia (basal activity of each promoter is dramatically increased within the tumor due to the hypoxic area present in pancreatic carcinoma tissues): promoter region from GRP78 gene (Glucose-regulated protein 78) and promoter region from GRP94 gene (Glucose-regulated protein 94) for dck::umk fusion and sst2 respectively. Constitutive mammalian promoters include, but are not limited to, the promoters for the following genes: hypoxanthine phosphoribosyl transferase (HPTR), adenosine deaminase, pyruvate kinase, beta.-actin promoter, muscle creatine kinase promoter, human elongation factor promoter and other constitutive promoters. Exemplary viral promoters which function constitutively in eukaryotic cells include, for example, promoters from the simian virus (e.g., SV40), papilloma virus, adenovirus, human immunodeficiency virus (HIV), cytomegalovirus (CMV), Rous sarcoma virus (RSV), hepatitis B virus (HBV), the long terminal repeats (LTR) of Moloney leukemia virus and other retroviruses, and the thymidine kinase promoter of herpes simplex virus. Others constitutive promoters are known to those of ordinary skill in the art. The promoters useful as gene expression sequences of the invention also include inducible promoters. Inducible promoters are expressed in the presence of an inducing agent. For example, the metallothionein promoter is induced to promote transcription and translation in the presence of certain metal ions. Others inducible promoters are known to those of ordinary skill in the art.

In general, the gene expression sequence shall include, as necessary, 5′ non-transcribing and 5′ non-translating sequences involved with the initiation of transcription and translation, respectively, such as a TATA box, capping sequence, CAAT sequence, and the like. Especially, such 5′ non-transcribing sequences will include a promoter region which includes a promoter sequence for transcriptional control of the operably joined antigen nucleic acid. The gene expression sequences optionally include enhancer sequences or upstream activator sequences as desired.

As used herein, nucleic acid sequences encoding the proteins sst2, dck and umk, and the gene expression sequence are said to be “operably linked” when they are covalently linked in such a way as to place the expression or transcription and/or translation of the protein coding sequences under the influence or control of the gene expression sequence. Two DNA sequences are said to be operably linked if induction of a promoter in the 5′ gene expression sequence results in the transcription of the proteins and if the nature of the linkage between the two DNA sequences does not (1) result in the introduction of a frame-shift mutation, (2) interfere with the ability of the promoter region to direct the transcription of the polypeptide of the invention, or (3) interfere with the ability of the corresponding RNA transcript to be translated into a protein.

The nucleic acid coding for the proteins sst2, dck and umk may be delivered in vivo alone or in association with a vector. In its broadest sense, a “vector” is any vehicle capable of facilitating the transfer of the nucleic acid coding for the proteins sst2, dck and umk to the cells. Preferably, the vector transports the nucleic acid to cells with reduced degradation relative to the extent of degradation that would result in the absence of the vector. In general, the vectors useful in the invention include, but are not limited to, plasmids, phagmids, viruses, other vehicles derived from viral or bacterial sources that have been manipulated by the insertion or incorporation of the peptidic antagonist nucleic acid sequences.

Preferred viral vectors for certain applications are the adeno-viruses and adeno-associated viruses, which are double-stranded DNA viruses that have already been approved for human use in gene therapy. The adeno-associated virus can be engineered to be replication deficient and is capable of infecting a wide range of cell types and species. It further has advantages such as, heat and lipid solvent stability; high transduction frequencies in cells of diverse lineages, including hemopoietic cells; and lack of superinfection inhibition thus allowing multiple series of transductions. Reportedly, the adeno-associated virus can integrate into human cellular DNA in a site-specific manner, thereby minimizing the possibility of insertional mutagenesis and variability of inserted gene expression characteristic of retroviral infection. In addition, wild-type adeno-associated virus infections have been followed in tissue culture for greater than 100 passages in the absence of selective pressure, implying that the adeno-associated virus genomic integration is a relatively stable event. The adeno-associated virus can also function in an extrachromosomal fashion.

The nucleic acid vector can include selectable markers that are active both in bacteria and in mammalian cells.

According to still another embodiment, the previously described nucleic acid sequences correspond to “naked DNA” like plasmids, cosmids or phagemids, preferably to at least one plasmid vector, and most preferably to one plasmid vector.

Plasmid vectors have been extensively described in the art and are well known to those of skill in the art. See e.g., SANBROOK et al., “Molecular Cloning: A Laboratory Manual,” Second Edition, Cold Spring Harbor Laboratory Press, 1989. In the last few years, plasmid vectors have been used as DNA vaccines for delivering antigen-encoding genes to cells in vivo. They are particularly advantageous for this because they do not have the same safety concerns as with many of the viral vectors. These plasmids, however, having a promoter compatible with the host cell, can express a peptide from a gene operatively encoded within the plasmid. Some commonly used plasmids include pBR322, pUC18, pUC19, pRC/CMV, SV40, and pBlueScript. Other plasmids are well known to those of ordinary skill in the art. Additionally, plasmids may be custom designed using restriction enzymes and ligation reactions to remove and add specific fragments of DNA. Plasmids may be delivered by a variety of parenteral, mucosal and topical routes. For example, the DNA plasmid can be injected by intramuscular, intradermal, subcutaneous, or other routes. It may also be administered by intranasal sprays or drops, rectal suppository and orally. It may also be administered into the epidermis or a mucosal surface using a gene-gun. The plasmids may be given in an aqueous solution, dried onto gold particles or in association with another DNA delivery system including but not limited to liposomes, dendrimers, cochleate and micro encapsulation.

In another preferred embodiment, the nucleic acid encoding for the proteins sst2, dck and umk are comprised in a plasmid vector.

Advantageously, said plasmid vector has the sequence SEQ ID NO:11 and comprises nucleic acid sequences coding for the Homo sapiens somatostatin 2 receptor protein and for a polypeptide comprising the two proteins Homo sapiens deoxycytidine kinase protein (dck) and Homo sapiens uridine monophosphate kinase protein (umk) linked by the cleavable FMDV (Foot-and-Mouth-Disease virus) 2A peptide.

Such “naked DNA” or plasmid(s) vector(s) is preferably associated with non-lipid cationic polymers (WU and WU, J. Biol. Chem., vol. 263, p: 14621-4, 1988), such as polyethylenimine (PEI) as disclosed in EP 0770140 or liposomes (BRIGHMAN et al., Am. J. Med. Sci., vol. 298, p: 278-81, 1989) to form complexes enhancing cellular uptake.

Advantageously, such naked DNA or plasmid(s) vector(s) is associated with non-lipid cationic polymers, preferably with polyethylenimine (PEI) as disclosed in EP 0770140.

In a specific embodiment, the products of the invention further comprise at least one pharmaceutically acceptable carrier.

The phrase “pharmaceutically acceptable” refers to molecular entities and compositions that are physiologically tolerable and do not typically produce an allergic or similar untoward reaction, such as gastric upset, dizziness and the like, when administered to a human. Preferably, as used herein, the term “pharmaceutically acceptable” means approved by a regulatory agency of the Federal or a state government or listed in the U.S. Pharmacopeia or other generally recognized pharmacopeia for use in animals, and more particularly in humans.

The term “carrier” refers to a diluent, adjuvant, excipient, or vehicle with which the compound is administered. Such pharmaceutical carriers can be sterile liquids, such as water and oils, including those of petroleum, animal, vegetable or synthetic origin, such as peanut oil, soybean oil, mineral oil, sesame oil and the like. Water or aqueous solution saline solutions and aqueous dextrose and glycerol solutions are preferably employed as carriers, particularly for injectable solutions. Suitable pharmaceutical carriers are described in “Remington's Pharmaceutical Sciences” by E. W. Martin.

The nucleic acid sequences or the nucleic acid vectors or Gemcitabine may be solubilized in a buffer or water or incorporated in emulsions and microemulsions. Suitable buffers include, but are not limited to, phosphate buffered saline Ca⁺⁺/Mg⁺⁺ free (PBS), phosphate buffered saline (PBS), normal saline (150 mM NaCl in water), Tris buffer and surfactants.

According to still another specific embodiment, the nucleic acid sequences described previously are administrated by intra-tumoral injection, preferably by intra-tumoral endoscopic ultrasound injection (i.e., echoendoscopy) as disclosed in HECHT et al. (Clin. Cancer Res., vol. 9, p: 555-61, 2003) as an example.

According to another specific embodiment, gemcitabine is administrated by intravenous route.

According to the present invention, an “effective amount” of a composition is one which is sufficient to achieve a desired biological effect, in this case inducing apoptosis in tumor cells and inhibiting metastazing. It is understood that the effective dosage will be dependent upon the age, sex, health, and weight of the recipient, kind of concurrent treatment, if any, frequency of treatment, and the nature of the effect desired. The ranges of effective doses provided below are not intended to limit the invention and represent preferred dose ranges. However, the preferred dosage can be tailored to the individual subject, as is understood and determinable by one of skill in the art, without undue experimentation.

As an example, an effective amount of a plasmid vector having the sequence SEQ ID NO:11 for an intra-tumoral injection depends on the tumor volume and is comprised between 1 and 1,000 μg of DNA per cm³ of tumor, preferably between 5 and 500 μg/cm³, more preferably between 8 and 500 μg/cm³.

As an example, an effective amount of gemcitabine corresponds to an administration of gemcitabine at 1000 mg/m² (of patient surface) per day. Such an administration is realized once a week during four consecutive weeks.

Surprisingly, the inventors have established that the intra-tumoral injection of the plasmid having the sequence SEQ ID NO:11 enables to obtain a tumor regression in combination with a dose of gemcitabine lower than the dose used for conventional pancreatic cancer treatment (⅔ of the normal gemcitabine dose).

Thus, in a preferred embodiment, an effective amount of gemcitabine corresponds to a dose of equal or less than 750 mg/m² per day. Such an administration is realized once a week during four consecutive weeks as previously.

Preferably, an effective amount of gemcitabine corresponds to a dose of 500 mg/m² per day, and once a week during four consecutive weeks as previously.

In the following, the invention is described in more detail with reference to nucleic acid sequences and the examples. Yet, no limitation of the invention is intended by the details of the examples. Rather, the invention pertains to any embodiment, which comprises details which are not explicitly mentioned in the examples herein, but which the skilled person finds without undue effort.

EXAMPLES I Treatment of Pancreas Cancer

1) sst2 and DCK:UMK/Gemcitabine Combination Sensitizes Pancreatic Cancer Cells to Death In Vitro:

BxPC-3 and MiaPaca-2 cells, derived from human pancreatic ductal carcinoma (DELESQUE et al., Cancer Research, vol. 57, p: 956-962, 1997) were maintained in RPMI 1640 medium (INVITROGEN) supplemented with 5% foetal calf serum (FCS; IN VITROGEN), fungizone (IN VITROGEN), antibiotics (streptomycin, penicillin, SIGMA), L-glutamine (INVITROGEN), and an anti-mycoplasma reagent (PLASMOCIN™, CAYLA).

Human pancreatic cancer cells were plated in 35-mm-diameter dishes at 50×10³ cells/ml (2 ml per dish) in RPMI 1640 containing 5% FCS. After a 12 h attachment phase, cells were transfected with 5 μg of a mock vector or with 5 μg of plasmid comprising a fusion cDNA DCK:UMK comprising the self cleaving FMDV 2A peptide inserted between DCK and UMK cDNAs with (pHNeo Sst2 DCK::UMK; FIG. 1) or without (pHDuo14 LGFP DCK-UMK; FIG. 2) the human sst2 cDNA (CAYLA) using linear polymers of ethyleneimine (PEI or L-PEI) with a mean molecular mass of 22 kDa (POLYPLUS-Transfection) (ratio PEI nitrogen to DNA phosphate N/P=8 to 10). PEI-DNA complexes were prepared in 5% (w/v) glucose. After 24 h of cell culture in RPMI 1640 containing 5% FCS, medium were replaced by fresh medium supplemented or not with increasing concentrations of gemcitabine (0.05 to 5 μg/ml) and cell counting was performed after 48 h of culture.

The results show that the combined expression of UMK, DCK and of SST2 sensitizes tumor cells to gemcitabine.

2) The Combination of sst2 and DCK:UMK/Gemcitabine Inhibits Growth of Pancreatic Tumors In Vivo:

PC1.0 cells, derived from a pancreatic ductal carcinoma induced by N-nitrosobis(2-oxopropyl)amine in Syrian golden hamsters (BENALI et al., Proc. Natl. Acad. Sci. USA, vol. 97, p: 9180-9185, 2000) were maintained in RPMI 1640 medium (INVITROGEN) supplemented with 5% foetal calf serum (FCS; INVITROGEN), fungizone (INVITROGEN), antibiotics (streptomycin, penicillin, SIGMA), L-glutamine (INVITROGEN), and an anti-mycoplasma reagent (PLASMOCIN™, CAYLA).

For stable transfection, PC1.0 cells were plated in 60-mm diameter dishes (2×10⁵ cells per dish) in 4 ml of RPMI 1640 containing 5% FCS. After a 12 h attachment phase, cells were transfected with 5 μg of the mock vector (VERNEJOUL et al., Cancer Research, vol. 62, p: 6124-31, 2002), of plasmid comprising a fusion cDNA DCK:UMK comprising the self cleaving FMDV 2A peptide inserted between DCK and UMK cDNAs (pHNeo Sst2 DCK::UMK; FIG. 1) or without (pHDuo14 LGFP DCK-UMK; FIG. 2) the human sst2 cDNA (CAYLA) using lipid cationic molecule (LyoVec™, CAYLA) (ratio lipid to DNA w/w=1:6). Stable clonal populations were selected in the presence of 0.4 to 0.6 mg/ml zeocin. Stable transfectants were then cultured in RPMI 1640 medium containing 5% SVF and 0.3 mg/ml zeocin.

Five-week-old male Syrian golden hamsters (GANNAT) were acclimatized in a temperature-controlled room under a 12-h light/12-h dark schedule and receive pelleted diet and water.

PC1.0 cells or mixed populations of PC1.0.DCK:UMK.SST2 and PC1.0 wildtype cells were orthotopically implanted into hamsters. Briefly, under pentobarbital anaesthesia and after a small laparotomy, 5×10⁵ PC1.0 cells resuspended in 0.1 ml of FCS-free RPM′ medium 1640 were injected into the tail of the pancreas under microscope by means of a sterile 29G lymphography catheter set.

On day 7, during the exponential phase of primary pancreatic tumors, the animals were treated with gemcitabine or vehicle, NaCl 0.9%. Gemcitabine was administrated intra-peritoneally three times at a dose of 120 mg/kg/day at days 9, 11 and 13 post-implantation.

On day 15, the results have shown a complete recession of the tumor for the animals expressing DCK, UMK and SST2, whereas the gemcitabine only slow down the tumor progression in the animals which do not express these proteins.

3) In Vivo Transfer of the Combination of sst2 and DCK:UMK/Gemcitabine

PC1.0 cells were orthotopically implanted into hamsters as described previously. Eight days later, after median laparatomy under anaesthesia, tumor volume was measured and an intra-tumoral gene transfer was performed using in vivo PEI 22-kDa (ratio PEI nitrogen to DNA phosphate N/P=10) in 5% glucose. PEI/DNA complexes were then injected into exponentially growing tumors using a sterile 29-Gauge lymphography catheter set with a flow rate of 25 μl/min. A total of 25 to 50 μg of DCK:UMK or DCK:UMK:SST2 expression vectors were injected. Animals were then i.p injected with NaCl 0.9% or gemcitabine (80 to 120 mg/kg/day every three days). Tumor volumes and progression were evaluated after sacrifice at day 15 post-cell implantation.

The tumor progression after ex vivo and in vivo gene expression and metastasis evolution results are listed in the following tables I and II.

TABLE I Tumor progression Tumor progression (percentage) No DNA, No Gemcitabine +800 to 1060 Gemcitabine, No DNA +150 to 378  DCK:UMK:SST2 +200 DCK:UMK, Gemcitabine  −60 DCK:UMK:SST2, Gemcitabine −15 to −30

TABLE II Number of metastatic sites Number of metastatic sites (percentage) No DNA, No Gemcitabine 100 (control) DCK:UMK 82 DCK:UMK:SST2 100 DCK:UMK, Gemcitabine 47.6 DCK:UMK:SST2, Gemcitabine 12.2

The results established that the expression of the fusion DCK:UMK in some tumor cells in combination with an administration of gemcitabine results in tumor regression (table I).

The results established also that the intra-tumor injection of fusion DCK::UMK and SST2 in combination to gemcitabine results in tumor regression even at a lower dose than normally applied: 120 mg/kg applied in hamster corresponds to a dose of 1000 mg/m² in human. Thus 80 mg/kg of gemcitabine in hamster (that also induced a tumor regression when co-administered with DCK::UMK and SST2) correspond to ⅔ of regular dose applied in human. The intra-tumor injection of DCK::UMK and SST2 allows reducing the dose of gemcitabine without alteration of the antitumor effect.

The results also established that the expression of SST2 (DCK:UMK:SST2 without gemcitabine; table II) does not inhibit tumor metastazing, whereas the combined expression of DCK:UMK with gemcitabine treatment inhibit tumor metastazing by two fold. Unexpectedly, the coexpression of SST2 with DCK:UMK associated with gemcitabine treatment results in a strong inhibition of tumor metastazing—i.e. nearly ten fold reduction-.

Finally, the results have established that the injection of plasmids has never resulted in an immediate or delayed allergic reaction in any of the treated animals. Moreover, the intra-tumoral administration of the therapeutic vector coexpressing SST2 and DCK:UMK do not result in any animal in a general toxicity—i.e., survival-, a regional toxicity—i.e., stomach, liver, spleen or peritoneum- or in a local toxicity—i.e., normal adjacent pancreas-.

4) Human Gene Therapy Using the Combination of sst2 and DCK:UMK/Gemcitabine

24 patients suffering from non resecable adenocarcinoma pancreatic cancer are selected.

125 μg, 250 μg, 500 μg, and 1 mg of pHNeo Sst2 DCK::UMK plasmid (CAYLA, SEQ ID NO: 11) are complexed in 5% glucose with linear polyethyleneimine derivative (jetPET™, POLYPLUS, ratio PET nitrogen to DNA phosphate N/P=10) according to the manufacturer instruction. The resulting complexes are lyophilised in 5 ml vial. Preliminary to the patient injection, the complexes are reconstituted in 2.5 ml of sterile water for injection and maintained at room temperature during 10 minutes before use.

Four groups of 6 patients are subjected to an intra-tumoral administration of the complexes comprising 125 μg, 250 μg, 500 μg, and 1 mg of DNA respectively (escalating dose starting by the lower dose i.e. the first 6 patients receive 125 μg, the new 6 patients 250 μg and following). Said administration step is realized by endoscopic ultrasound injection that is performed at day one.

On day 3, the treated patients are perfused for an intravenous administration of 1000 mg/m² of gemcitabine (GEMZAR®) during 30 minutes. Similar perfusions are realized on days 10, 17, and 24 following the plasmid intra-tumoral administration.

The daily evolution of the tumor progression is established for all the patients and, on day 29, a second intra-tumoral plasmid administration is realized on the four groups of 6 patients as described previously.

On days 31, 38, and 45 the treated patients are perfused for an intravenous gemcitabine administration as described previously.

The daily evolution of the tumor progression is established for all the patients until day 60.

The average of human pancreas tumor volume is 32 cm³±8. Considering the experiences realized in animals and on a tumor of 30 cm³, the dose of 125 μg of DNA (4.17 μg/cm³) should be inefficient for inhibiting tumor progression, whereas the dose of 250 μg of DNA (8.35 μg/cm³) and greater should be efficient for treating pancreas cancer and for inhibiting the metastazing of pancreas cancer.

II Treatment of Other Cancers

1) sst2 and DCK:UMK/Gemcitabine Combination Sensitizes Hepatocellular Carcinoma and Hepatoma Cells to Death In Vitro:

HuH7 cells, derived from human hepatocellular carcinoma, and HepG2 cells derived from hepatoma were plated in 35-mm-diameter dishes at 50×10³ cells/ml (2 ml per dish) in DMEM culture medium. After a 12 h attachment phase, cells were transfected with 5 μg of a mock vector or with 5 μg of plasmid comprising a fusion cDNA DCK:UMK comprising the self cleaving FMDV 2A peptide inserted between DCK and UMK cDNAs with (pHNeo Sst2 DCK::UMK; FIG. 1) the human sst2 cDNA (CAYLA) using linear polymers of ethyleneimine (PEI or L-PEI) with a mean molecular mass of 22 kDa (POLYPLUS-Transfection) (ratio PEI nitrogen to DNA phosphate N/P=8 to 10). PEI-DNA complexes were prepared in 5% (w/v) glucose. After 24 h of cell culture in DMEM containing 10% FCS, medium were replaced by fresh medium supplemented or not with increasing concentrations of gemcitabine (0.05 to 5 μg/ml) and cell counting was performed after 48 h of culture.

The results show that the combined expression of UMK, DCK and of SST2 drastically sensitizes tumor cells derived from HCC and hepatoma to gemcitabine. 

1. A method for treating cancer comprising the simultaneous, separate, or sequential administration of: (i) at least one nucleic acid sequence coding for the human somatostatin 2 receptor protein (sst2) comprising the sequence SEQ ID NO:1, or an ortholog or derivative thereof, (ii) at least one nucleic acid sequence coding for the human deoxycytidine kinase protein (dck) comprising the sequence SEQ ID NO:2, or an ortholog or derivative thereof, (iii) at least one nucleic acid sequence coding for the human uridine monophosphate kinase protein (umk) comprising the sequence SEQ ID NO:3, or an ortholog or derivative thereof, and (iv) gemcitabine, to a patient in need thereof.
 2. The method of claim 1, for the inhibition of tumor metastazing.
 3. The method of claim 1, for treating pancreatic cancer.
 4. The method of claim 1, for treating hepatocellular carcinoma.
 5. The method of claim 1, wherein said patient is a human.
 6. The method of claim 1, comprising the administration of at least one nucleic acid sequence coding simultaneously for the human deoxycytidine kinase protein (dck) comprising the sequence SEQ ID NO:2, or an ortholog or derivative thereof, and for the human uridine monophosphate kinase protein (umk) comprising the sequence SEQ ID NO:3, or an ortholog or derivative thereof.
 7. The method of claim 6, comprising the administration of at least one nucleic acid sequence coding for a polypeptide comprising the two proteins Homo sapiens deoxycytidine kinase protein (dck) and Homo sapiens uridine monophosphate kinase protein (umk) linked by the cleavable Foot-and-Mouth-Disease virus (FMDV) 2A peptide, which polypeptide comprises the sequence SEQ ID NO:
 10. 8. The method of claim 1, wherein said nucleic acid sequences are comprised within at least one vector.
 9. The method of claim 8, wherein said plasmid vector comprises the sequence SEQ ID NO:11, and comprises nucleic acid sequences coding for the Homo sapiens somatostatin 2 receptor protein and for a polypeptide comprising the two proteins Homo sapiens deoxycytidine kinase protein (dck) and Homo sapiens uridine monophosphate kinase protein (umk) linked by the cleavable Foot-and-Mouth-Disease virus (FMDV) 2A peptide.
 10. The method of claim 8, wherein said plasmid(s) vector(s) is associated with non-lipid cationic polymers.
 11. A pharmaceutical composition comprising: (i) at least one nucleic acid sequence coding for the human somatostatin 2 receptor protein (SST2) comprising the sequence SEQ ID NO: 1, or an ortholog or derivative thereof, (ii) at least one nucleic acid sequence coding for the human deoxycytidine kinase protein (DCK) comprising the sequence SEQ ID NO: 2, or an ortholog or derivative thereof, and (iii) at least one nucleic acid sequence coding for the human uridine monophosphate kinase protein (UMK) comprising the sequence SEQ ID NO: 3, or an ortholog or derivative thereof.
 12. The pharmaceutical composition according claim 11, wherein said nucleic acid sequences are comprised within a plasmid vector comprising the sequence SEQ ID NO:11, and comprising nucleic acid sequences coding for the Homo sapiens somatostatin 2 receptor protein and for a polypeptide comprising the two proteins Homo sapiens deoxycytidine kinase protein (dck) and Homo sapiens uridine monophosphate kinase protein (umk) linked by the cleavable Foot-and-Mouth-Disease virus (FMDV) 2A peptide.
 13. The pharmaceutical composition according claim 12, wherein said plasmid vector is associated with polyethylenimine (PEI).
 14. A plasmid vector comprising the sequence SEQ ID NO:11, and comprising nucleic acid sequences coding for the Homo sapiens somatostatin 2 receptor protein and for a polypeptide comprising the two proteins Homo sapiens deoxycytidine kinase protein (dck) and Homo sapiens uridine monophosphate kinase protein (umk) linked by the cleavable Foot-and-Mouth-Disease virus (FMDV) 2A peptide.
 15. The method according to claim 3, wherein said gemcitabine is administrated at a dose of equal or less than 750 mg/m² per day.
 16. The method of claim 8, wherein said vector is a plasmid vector.
 17. The method of claim 10, wherein the non-lipid cationic polymers are polyethylenimine (PEI). 